Nevada and California authorities issued an Amber Alert yesterday for an 8-year-old Nevada girl they believe was kidnapped by a convicted sex offender.

San Diego County law enforcement agencies reported responding to possible sightings of Lydia Rupp, but none panned out.

Officials believe Fernando Aguero, 47, may have headed toward Mexico with Lydia. Aguero is believed to have relatives in San Diego and Las Vegas.

Lydia was reported missing by her mother about 11:30 p.m. Friday. She lives in Fernley, Nev., east of Reno. Her mother met Aguero at a church and befriended him, said Capt. Jeff Page of the Lyon County Sheriff's Department in Nevada.

The mother told sheriff's deputies that all the photographs of her daughter had been taken as well as her birth certificate and Social Security card.

Lydia is 4 feet 9 inches tall and weighs 85 pounds. She has brown hair, brown eyes and scars on her cheeks from dog bites.

Aguero uses aliases and is 5 feet 10 and weighs 150 pounds. He has brown eyes, salt-and-pepper hair and a dark mustache.

Aguero was last seen driving a bluish-silver 2001 Kia Rio without license plates.